Across
- 2. a pyroclastic igneous rock formed from the consolidation and cementation of volcanic ash, tephra, and other debris ejected during explosive eruptions
- 3. the natural, dynamic actions that shape, alter, and recycle Earth’s physical structures, materials, and surface over time
- 6. complete and permanent disappearance of a species from Earth, with no living individuals remaining to reproduce
- 7. a combustible, black/brownish-black sedimentary rock, rich in carbon, formed over millions of years from compressed, chemically altered plant matter through intense heat and pressure
- 9. a primary sedimentary structure characterized by inclined layers [forest beds] deposited at an angle to the main horizontal bedding plane;
Down
- 1. an international, standardized reference system used by geoscientists to organize billion-year
- 4. the largest division of geologic time, representing vast spans of hundreds of millions to billions of years, marking major phases in Earth’s history
- 5. comprehensive, physical chronicle of Earth’s history, documented within layers of sedimentary, igneous, and metamorphic rocks
- 6. a major, long-term division of Earth’s history characterized by significant, distinct, and defining geological, climatic, and biological changes; a subdivision of an eon
- 8. a specific significant subdivision of geologic time representing a distinct chapter in Earth’s history; often marked by specific fossil records or rock layers; a subdivision of periods